Fig. 5 ∣. Conceptual framework for action error computation.

The available actions under a given task rule and stimulus are predicted by action forward models (light blue). This includes both the correct response (target) and the incorrect response (distractor). The action selection process (red box) then chooses between one of the possible actions. Action selection is modulated by the control command (blue line), which is composed of proactive and reactive components (blue). The feedback controllers use performance-monitoring information from the prior trial to provide reactive control, and the control inverse model provides proactive control based on the task rules. Three kinds of performance-monitoring signals are computed (none of which depends on external feedback). The red cross computes action error signals by comparing the selected action, conveyed as corollary discharge 1, with the predicted goal-compatible action. The orange cross computes ex post conflict signals that are the result of comparing the selected action, conveyed as corollary discharge 1, with the predicted goal-incompatible action. The dark red cross computes control prediction error by comparing the predicted control outcome and the actual control outcome (error, conflict); it can also recruit feedback control. Action errors and ex-post conflict are used to predict the occurrence of reward. The control forward model predicts whether the current control settings, conveyed as corollary discharge 2, will result in an action error and/or ex post conflict. The extent to which feedback control was recruited is provided to the control inverse model as corollary discharge 3. Light blue boxes are forward models (predictors), dark blue boxes are controllers and the red box is action selection. Dark blue arrows are corollary discharges.